Insulation performance of safety-related electrical penetrations for pressurized water reactors under simulated severe accident conditions

Aiki Watanabe, Masaaki Ikeda, Takefumi Minakawa, Naoshi Hirai, Yoshimichi Ohki

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Electrical penetrations (EPs) in nuclear power plants play important roles in keeping a primary containment vessel airtight and in connecting electrical cables from the inside to the outside. Safety-related EPs, which are categorized as “severe-accident (SA) equipment,” are required to maintain their intended functions under various SA environmental conditions after having been aged under the normal operating conditions throughout their service lives. To investigate the insulation performance of EPs in a SA environment, we tested two EPs that are equivalent to those used in pressurized water reactors in Japan. One EP specimen was pre-aged in a concurrent thermal and radiation environment at 100 °C and 100 Gy/h for several thousand hours to simulate the degradation induced during the designated service period. The other EP specimen was used without pre-aging. To simulate the degradation induced by radiation during a SA, the EPs were irradiated with gamma rays to a total dose of 500 kGy at a dose rate of 7 kGy/h. Subsequently, the EP specimens were exposed to saturated steam at 155 °C and 0.45 MPaG for 168 h. The electrical insulation resistance between the insulated cores of cables in each EP specimen were monitored during the steam exposure. The minimum insulation resistances that we measured during the steam exposure for EP specimens with and without the pre-aging are about 109 and 108 £1, respectively, confirming that they retain sufficiently good insulation performance.

Original languageEnglish
Title of host publicationProceedings of 2020 International Symposium on Electrical Insulating Materials, ISEIM 2020
PublisherInstitute of Electrical Engineers of Japan
Pages225-228
Number of pages4
ISBN (Electronic)9784886864185
Publication statusPublished - 2020 Sep 13
Event2020 International Symposium on Electrical Insulating Materials, ISEIM 2020 - Virtual, Tokyo, Japan
Duration: 2020 Sep 132020 Sep 17

Publication series

NameProceedings of the International Symposium on Electrical Insulating Materials
Volume2020-September

Conference

Conference2020 International Symposium on Electrical Insulating Materials, ISEIM 2020
CountryJapan
CityVirtual, Tokyo
Period20/9/1320/9/17

Keywords

  • Electric penetration
  • Nuclear power plant
  • Severe accident
  • Steam exposure

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials

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